Wednesday, April 1, 2009

"Smooth" Carbon Nanotube Breakthrough

Imagine you are looking through a very high-powered microscope at the smallest tube in the world – a single-walled carbon nanotube so tiny that a million can fit on the head of a pin.

Imagine too that the exterior of the tube is covered in small irregular bumps caused by oxygen molecules that cling to the outside like barnacles on a pier. Now imagine trying to slide something – a slightly larger tube perhaps – over the bumpy tube to smooth out the surface.

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But now, chemistry professor Fotios Papadimitrakopoulos and a team of researchers in the Nanomaterials Optoelectronics Laboratory at the Institute of Materials Science have found a way to smooth the surface of nanotubes, in whatPapadimitrakopoulos describes as a major nanotechnology breakthrough that could have significant applications in medical imaging and other areas.

By developing a process in which a chemical ‘sleeve’ tightly wraps itself around the nanotube, Papadimitrakopoulos managed to not only create a smooth new surface on the nanotube but also to ‘clean’ its underlying exterior of defects in a way that has never been accomplished before.

Carbon nanotubes have traditionally been very poor emitters of light because of their bumpy exterior defects and have therefore been limited in some of their echnological and medical applications.

As a result of the newly discovered wrapping process, Papadimitrakopoulos managed to increase the luminescence efficiency – the light emitting capability – of the nanotube 40-fold.

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Increasing the luminescence efficiency of carbon nanotubes may someday make it possible for doctors to inject patients with microscopic nanotubes to detect tumors, arterial blockages, and other internal problems.

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Their luminescence also allows them to readily integrate with silicon-basedtechnology. This provides an enormous repertoire for nanotube use in advanced fiber optics components, infrared light modulators, and biological sensors.

The key to the discovery was a flavin-based (Vitamin B2) helical wrapping that formed an especially tight and seamless barrier around the nanotube.

A computer animation of the carbon nanotube wrapping process can be found here.